The incidence of Acinetobacter baumannii
infection has greatly increased over recent decades with
infections occurring more in
critically ill hospitalised patients. Hospital outbreaks of multiple
antibiotic-resistant strains are posing an increasing threat to public health. Three different outbreaks of multidrug-resistant A. baumannii (MRAB)
infections involving 24 patients, aged 16-75 years occurred in the intensive care unit in the course of one year. The isolates were cultured from clinical samples and identified using automated Vitek II ID system and the API 20NE system. Susceptibility testing was done by the E-test method. Molecular typing of the isolates was determined by pulsed-field electrophoresis. Screening of both patients and the environment was carried out. The acquisition time, i.e. the time of admission to time of acquiring
infection, ranged from 3 to 31 days. All isolates were multiply resistant (MRAB), including resistance to
carbapenems (MRAB-C) in the majority of cases but susceptible to
tigecycline, with a minimum inhibitory concentration (MIC(90)) of 2 microg/mL. The overall mortality rate was 16.7%. Time-to-clearance of the MRAB-C was 8.3 days in the first outbreak, when
tigecycline was not used, and 2.8 and 3.1 days during the second and third outbreaks, respectively, when
tigecycline was used, and all but one patient survived. Environmental screening revealed gross contamination of many surfaces and equipment within the unit. The outbreak strains belonged to two distinct clones (D and E) whereas the 14 environmental strains belonged to three distinct groups (A-C). The outbreak of
infections treated with
tigecycline was successfully eliminated in conjunction with an aggressive infection control strategy.